Question: Solve for $x$ : $x^2 + 3x - 4 = 0$
Answer: The coefficient on the $x$ term is $3$ and the constant term is $-4$ , so we need to find two numbers that add up to $3$ and multiply to $-4$ The two numbers $-1$ and $4$ satisfy both conditions: $ {-1} + {4} = {3} $ $ {-1} \times {4} = {-4} $ $(x {-1}) (x + {4}) = 0$ Since the following equation is true we know that one or both quantities must equal zero. $(x -1) (x + 4) = 0$ $x - 1 = 0$ or $x + 4 = 0$ Thus, $x = 1$ and $x = -4$ are the solutions.